The invention is located in the field of medical instrumentation; more specifically catheters intended to be introduced into the blood of lymph stream of patients.
The present invention relates to a device for introducing a flexible guide wire, with a J-shaped end, inside the circulatory system of a patient, this guide wire subsequently allowing placement of a catheter.
Central venous catheters may be introduced into the veins by sliding around a spiral and flexible guide, the latter having been introduced therein beforehand by means of a needle.
This technique is known to one skilled in the art under the name of the “Seldinger technique”. It will now be briefly described with reference to the enclosed FIGS. 1A-1F I which are diagrams illustrating the main steps.
Referring to FIG. 1A, it may be seen that when a practitioner wants to insert a catheter into a vein, the walls of which are rather thin, to do this he/she uses a flexible spiral guide G, the distal end E of which has a shape curved on itself, said to be “J-shaped”. The specific shape of this distal end E enables it to be introduced into the inside of the vein, without either damaging the walls of the latter or piercing them.
However, it is necessary to straighten out the J-shaped distal end of this guide wire before introducing it into the vein. For this purpose, the practitioner uses a straightener R with a conical shape, provided with an axial lumen of small diameter. He/she introduces the guide wire G through the distal end E of the straightener R and exerts traction on the latter (arrow H), until the distal end E of this wire is straightened. It is then found in the situation illustrated in FIG. 1B.
Next, as this may be seen in FIG. 1C, the practitioner uses a syringe S provided with an aspiration needle A in order to pass through the skin P of the patient. Once the bevel of the needle A is in the flesh and under the skin, he/she pulls on the piston of the syringe (arrow I), thereby creating a vacuum in the latter and in the needle. The practitioner then pushes on the needle and when the bevel of the latter penetrates into the vein V, blood is sucked up inside the syringe S, so that he/she may visually ascertain that the bevel of the needle is properly positioned in the vein V.
The practitioner then removes the syringe S from the base of the needle A, this situation being illustrated in FIG. 1D. Next, he/she introduces into the interior of the base of the needle, the distal end of the straightener R, inside which the guide wire G is found in the straightened position.
The practitioner then pushes the guide wire G through the straightener R and the needle A, as far as into the vein v (arrow J). This situation is illustrated in FIG. 1E.
The small distance between the distal end of the straightener R and the proximal end of the base of the needle A does not allow the J-shaped end of the guide wire to bend, so that the latter is forced to move forward along a straight line as far as into the vein V.
Finally, the practitioner removes the straightener R and the needle A by sliding them along the guide wire G and he/she then engages the tube of the catheter C on the guide wire G (arrow K), until the catheter is engaged over a certain distance in the vein V, as illustrated in FIG. 1F. He/she is assisted for this by marks present on the tube of the catheter which allow it to be located.
This technique however has drawbacks in that it requires many manipulations and in that blood losses may be significant, notably when the syringe S is disconnected from the needle A, as this is illustrated in FIG. 1D.
Moreover, when it is desired to insert a catheter inside an artery, it will be noted that the guide wire G does no longer necessarily have a J-shaped end, since the walls of the arteries are more resistant and harder, the risk of piercing them is lesser.
The technique for introducing the catheter is the same as the one which was just described for a vein, except that it is no longer necessary to use a syringe for viewing blood backflow, and therefore the proper position of the bevel of the needle in the artery. However, taking into account the pressure prevailing inside arteries, blood losses may be much more significant before complete introduction of the guide wire G inside the artery.
In order to improve the Seldinger technique described earlier and also to limit blood losses, several devices have been developed. Two of them are described in documents WO 90/11098 and WO 99/12600.
These devices respectively consist in a syringe, the piston of which has been modified in order to allow introduction of a catheter without blood losses, and in a syringe provided with a switch.
However, these devices are complex, which make them more expensive to manufacture and more complicated to use. Indeed, upon using one of these two systems, the practitioner is found pricking with bulky equipment: the needle plus the syringe plus the guide straightener plus the wound guide in a protective tube. On the other hand, the guides are often long (twice the length of the catheter), and, in order to avoid that they hang about on the field before introduction (=lack of asepsis) they are in a long and bulky protective tube.
A connector capable of being mounted on an aspiration needle or between this needle and a syringe is also known from document U.S. Pat. No. 5,336,192, for introducing an angiography catheter inside a lymph or blood vessel.
This connector interiorly includes a slit elastomeric disk. When the connector is connected to a syringe, the cone of the latter moves the walls of the disk apart, which allows communication between the syringe and the needle for vacuum and aspiration operations. After disconnecting the syringe, the disk closes back while preventing any loss of blood.
This document also describes the possibility of using a guide wire straightener and introducing the latter in the connector upstream from the elastomeric disk, and then of pushing the guide wire through the slit of this disk as far as into the vein.
However, such a device has the drawback of not being perfectly sealed, since it is difficult to guarantee the perfect seal of a slit around a guide wire of cylindrical shape.
The object of the invention is to find a remedy to these drawbacks.